The present invention relates to binoculars with double hinge and central adjustment for focussing.
The German printed patent application No. 2,233,055 discloses binoculars of that type wherein the two telescopes are interconnected by a double hinge bridge. The parts for focussing are located inside of the telescope tubes and are adjusted by elements which are centrally located, outside of the tubes. The adjustment elements include a spindle and a nut riding thereon and moving in axial direction. A connecting element extends from the nut towards the two tubes for connection to the focussing elements therein.
This known arrangement permits focussing of the two telescopes in unison, but the transfer mechanism between the adjusting spindle and the focussing elements in the telescopes are disposed outside of the telescope tubes as well as outside of the connecting bridge for the two telescopes. Moreover, the nut and other focussing elements require a certain amount of space for movement so that these parts must be sufficiently spaced from the bridge to permit that movement. Consequently, the transfer elements linking the nut with the focussing elements are exposed to damage, and to ambient weather conditions. It can readily be seen that any of these conditions may interfere with proper operation of the focussing mechanism. Also, all exposed parts must have undergone rather expensive surface treatment and finishing.